As the downscaling of Si-based MOSFETs, the SiO2 gate oxide thickness is correspondingly reduced to be close to the quantum tunneling limit of 1.0 nm. Beyond this point, electrons tunneling through this insulating layer will give unacceptably large electric leakage currents. HfO2-based high-κ dielectric was introduced to replace SiO2 in 45 nm CMOS technology as the solution to this issue. Moreover, to extend the Moore's Law beyond 15 nm node, it is adamant that III-V high electron mobility semiconductors integrated with high K gate dielectrics has to be employed.
Currently, the chemical vapor deposition (CVD), the atomic layer deposition (ALD), the metal organic chemical vapor deposition (MOCVD), the pulsed-laser deposition (PLD), sputtering, the molecular beam epitaxy (MBE) and so on are methods commonly used for forming a high dielectric constant film. Atomic layer deposition (ALD) is considered as one deposition method with the greatest potential for producing very thin, conformal films with control of the thickness and composition of the films possible at the atomic level. A major driving force for the recent interest is the prospective seen for ALD in scaling down microelectronic devices. However, when a stacked structure of the high-κ dielectric film and the substrate is formed by using the abovementioned methods, there exists a problem that an interface between the high-κ dielectric film and the substrate is always exposed to the atmosphere, which may cause the generation of the native oxide layer on the substrate, thereby giving adverse effects on the electric characteristics. Accordingly, a high-quality oxide/substrate interface is required for realizing high performance of MOSFETs.
The native oxides of III-V semiconductors, unlike SiO2 on Si, are leaky and do not perform high quality native III-V oxides/III-V semiconductors interfaces. Ex-situ chemical treatment using HCl+(NH4)2S is considered as the method most commonly used to remove native oxides and passivate III-V surface prior to the deposition of high-κ dielectrics. However, the method is not able to completely remove the native oxides. Moreover, the residual sulfur at oxide/semiconductor interface is thermally unstable and is adverse to the source/drain activation in MOSFET fabrication.
Hence, because of the defects in the prior arts, the inventors provide a method and system for manufacturing semiconductor devices to effectively overcome the demerits existing in the prior arts.